GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
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slasd0(l) |
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SLASD0 - a divide and conquer approach, SLASD0 computes the singular value decomposition (SVD) of a real upper bidiagonal N-by-M matrix B with diagonal D and offdiagonal E, where M = N + SQRE
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SUBROUTINE SLASD0( |
N, SQRE, D, E, U, LDU, VT, LDVT, SMLSIZ, IWORK, WORK, INFO ) | ||
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INTEGER |
INFO, LDU, LDVT, N, SMLSIZ, SQRE | ||
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INTEGER |
IWORK( * ) | ||
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REAL |
D( * ), E( * ), U( LDU, * ), VT( LDVT, * ), WORK( * ) |
Using a divide and conquer approach, SLASD0 computes the singular value decomposition (SVD) of a real upper bidiagonal N-by-M matrix B with diagonal D and offdiagonal E, where M = N + SQRE. The algorithm computes orthogonal matrices U and VT such that B = U * S * VT. The singular values S are overwritten on D.
A related subroutine, SLASDA, computes only the singular values, and optionally, the singular vectors in compact form.
N (input) INTEGER
On entry, the row dimension of the upper bidiagonal matrix. This is also the dimension of the main diagonal array D.
SQRE (input) INTEGER
Specifies the column dimension
of the bidiagonal matrix. = 0: The bidiagonal matrix has
column dimension M = N;
= 1: The bidiagonal matrix has column dimension M = N+1;
D (input/output) REAL array, dimension (N)
On entry D contains the main diagonal of the bidiagonal matrix. On exit D, if INFO = 0, contains its singular values.
E (input) REAL array, dimension (M-1)
Contains the subdiagonal entries of the bidiagonal matrix. On exit, E has been destroyed.
U (output) REAL array, dimension at least (LDQ, N)
On exit, U contains the left singular vectors.
LDU (input) INTEGER
On entry, leading dimension of U.
VT (output) REAL array, dimension at least (LDVT, M)
On exit, VT’ contains the right singular vectors.
LDVT (input) INTEGER
On entry, leading dimension of VT.
SMLSIZ (input) INTEGER On entry, maximum size of the subproblems at the bottom of the computation tree.
IWORK INTEGER work array.
Dimension must be at least (8 * N)
WORK REAL work array.
Dimension must be at least (3 * M**2 + 2 * M)
INFO (output) INTEGER
= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal
value.
> 0: if INFO = 1, an singular value did not converge
Based on
contributions by
Ming Gu and Huan Ren, Computer Science Division, University
of
California at Berkeley, USA
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slasd0(l) | |